TEXAS COMMISSION on ENVIRONMENTAL QUALITY PROPOSED STUCTURE FOR CHAPTER 217 <Subchapter A Administrative Provisions <Subchapter B Design Bases <Subchapter C Convention Collection System PROPOSED STUCTURE FOR CHAPTER 217 <Subchapter D Alternative Sewer Collection System <Subchapter E Preliminary Treatment Units <Subchapter F Activated Sludge PROPOSED STUCTURE FOR CHAPTER 217 <Subchapter G Fixed Film and Filtration <Subchapter H Natural Systems <Subchapter I On-site Treating Over 5,000 Gallons Per Day PROPOSED STUCTURE FOR CHAPTER 217 <Subchapter J Sludge <Subchapter K Disinfection <Subchapter L Safety SUBCHAPTER A Administrative Provisions <The proposed rule grandfathers existing facilities to the rule which was in place at the time of the facility's construction and original plans and specifications approval. This will tell the engineer and the owner of the facility what parts of a plant that will have to meet the latest design criteria during a upgrade or modification. <The rule requires an operation and maintenance manual to be developed as part of the facility design. The rule provides guidance regarding which types of information should be included in the O&M manual. The existing criteria only stated O&M manual be furnished to the system owner. <Clarifies TCEQ will not enforce or review for compliance with rules of other entities. SUBCHAPTER B Design Bases <The major change to this subchapter is to allow the design engineer to design the plant based on the annual average flow instead of the max. monthly flow. This will allow a city to design small treatment units or to utilize existing units without need for some expansion. <The draft criteria will allow a city to rerate their plant based on a lower organic loading. The criteria provides options for rerating plants based on influent organic and flow data. <The draft criteria provide clearer description of the requirement for back-up power. <The criteria will have a section on the reuse of effluent within the treatment process when ever possible. SUBCHAPTER C Conventional Collection Systems SUBCHAPTER C Conventional Collection Systems <Gravity Pipes <Lift Stations and Force Main <Reclaimed Water and Irrigation Facilities SUBCHAPTER D Alternative Sewer Collection Systems <Vacuum System <Pressure Sewers <Small Diameter Variable Grade Sewer SUBCHAPTER E Preliminary Treatment Units <Removes the requirement for redundant fine screens if coarse screens and a bypass are provided, unless a credit for organic reduction as a result of the fine screen is desired. <The proposed criteria provides more detailed design requirements for grit removal chambers. <Requires flow measurement at all facilities and provides for more detailed design requirements regarding flow measurement. SUBCHAPTER F Activated Sludge SUBCHAPTER F Activated Sludge <Provides design criteria for sequencing batch reactors (SBR). <Provides a table to determine net solids production. <Provides the equation for determination of field transfer efficiency. <Draft rules state the minimum depths for diffuser submergence. <Provides air flow correction factors for various diffuser submergence depths. <Draft criteria changes the limitation on hopper bottom clarifiers from 25,000 gpd to 10,000 gpd or less. <The draft criteria requires multiple basin and clarifiers for flows greater than 400,000 gpd. SUBCHAPTER G Fixed Film Filtration SUBCHAPTER G Fixed Film Filtration <The major change to this part of the criteria is to give credit to trickling filters for nitrification. <The other changes are to provide the design engineer with better guidelines for their design of filters and fixed film reactors SUBCHAPTER H Natural System <More flexibility in the design of wetlands systems. <Updated criteria for overland flow systems. <Add greater flexibility for liner installations. <Criteria for evaporative pond systems. <Criteria for integrated facultative lagoons. <Re-instates the design criteria for Imhoff tanks. SUBCHAPTER J Sludge SUBCHAPTER J Sludge <Provides criteria for chemical pretreatment of residuals. <Provides design criteria for sludge dewatering units <Requires sludge storage for all facilities and provides design criteria for sludge storage. <Provides criteria for sludge thickening technologies including: Ímechanical thickeners, Ídissolved air flotation thickeners, and Ícentrifugal thickeners. SUBCHAPTER K Disinfection

Requirements for disinfection, dechlorination, post aeration and sampling point locations.

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